It is desired that strollers fulfil the following requirements. First, the main body of the stroller must be collapsible to a flat shape. Second, it must be easily collapsible and unfoldable to shape by anybody. Third, it must be free of the possibility of being inadvertently collapsed during use.
Conventional strollers are bulky, difficult to collapse and inconvenient to carry around for example in department stores, supermarkets, stations, etc., giving passerby trouble. Strollers are not adapted for carrying on a bus, train or the like and, when carried thereon, they are in fact troublesome to passengers. Moreover, they are inconvenient because of the large space needed for storage when out of use.